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variable scope in ruby a techno-preso-blogpost 16.10.13 charlotte chang

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first, the preamble the hardest thing about writing anything is the examples. ...picking good examples carries a book, right? If the examples are bad, you hate them. If the examples are engaging...they teach you the right things, then they keep your attention. -sandy metz Ruby Rogues

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many myriad missive mischievous multifarious massive multitudinous macabre mayhem merry magnificent marauding Mixed Metaphors

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Part I. mini journey into the veritable variable

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Variables are like nicknames. Remember when everyone used to call you Stinky Pete? People would say, “Get over here, Stinky Pete!” And everyone miraculously knew that Stinky Pete was you." -Why’s Poignant Guide to Ruby

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plain lowercase words can include letters, digits and _ syntax kale fat_puggle fly_hitops snuggie sarcasm _8tracks pink_scrunchie accordion bear_trap

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something you want to use frequently && you don’t want to type it over and over and over and over and over and over and over and over and over and over and over over ove why?

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something you want to use frequently this is a function but it could be... else?

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beaker beaker these are variables where you could put

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beaker beaker 6 * volume(beaker) == 2 * volume(beaker)

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1 * volume(beaker)

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variables can be named anything you want but they should be relevant and by the way, naming your variables with the same name is a bad idea.

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types of variables global $ instance @ or self. local [a-z] or _ constant [A-Z] class @@

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Part II. How I Learned to Stop Worrying and Love the Ruling Class

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newb’s journey into variable scope 5.steps do | easy | .hold

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newb’s journey into variable scope 5.steps do | easy | 1 5 Bourgeoisie Obamacare

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newb’s journey into variable scope 5.steps do | easy | 1 2 3 4 5 Bourgeoisie BenevolentBourgeoisie Canada OnePercent Obamacare

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1

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can the baker use the brewmaster’s tools? can the carpenter use the baker’s bandages? local variable scope 1

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what do you notice about the medicine(s)? local variable scope 1

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DRY Don’t Repeat Yourself The Pragmatic Programmer Andy Hunt and Dave Thomas 1

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2

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2 class instance variable scope who has the medicine? who can use the medicine? when is medicine used?

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Do one thing. curly’s law 2

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3

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3 constant scope when would the brewmaster get medicine? when would the brewmaster go to the doctor?

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3 constant scope who has to use wait_time? when/how does the brewmaster have to wait_time?

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3 constant scope what if there was a wait for beer? next year, the wait time increases to 10 weeks, what happens?

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3 No magic numbers. Steve McConnell

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4

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4 class variable scope do the brewmaster and the carpenter go to the same doctor? can the doctor prescribe medicine independent of a pharmaceutical company? if a doctor gets sued, where can s/he get money from?

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4 Class instance variables should usually be preferred over class variables. Github's Ruby Styleguide

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5

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5 global variable scope who can access healthcare? can new instances of America have healthcare? does America know where healthcare comes from?

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1. what is a variable? 2. what are the types of variables? 3. what is variable scope? 4. what are the types of variable scope? recap 1 2 3 4 5 Bourgeoisie BenevolentBourgeosie Canada OnePercent Obamacare local class instance constant class global

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<%= some_witty_ending %>